A Phase II Study of Denileukin Diftitox in Patients with Advanced Treatment Refractory Breast Cancer
<b>Background/Objectives</b>: Regulatory T cells (Treg) suppress immunity in the tumor microenvironment, are linked to poor prognosis across breast cancer subtypes, and suppress the cytolytic function of cytotoxic CD8+ T cells. Denileukin diftitox, a diphtheria toxin (DT)/IL-2 fusion pro...
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MDPI AG
2025-01-01
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| Online Access: | https://www.mdpi.com/2076-393X/13/2/117 |
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| author | William R. Gwin Lupe G. Salazar James Y. Dai Doreen Higgins Andrew L. Coveler Jennifer S. Childs Rosie Blancas Yushe Dang Jessica Reichow Meredith Slota Hailing Lu Mary L. Disis |
| author_facet | William R. Gwin Lupe G. Salazar James Y. Dai Doreen Higgins Andrew L. Coveler Jennifer S. Childs Rosie Blancas Yushe Dang Jessica Reichow Meredith Slota Hailing Lu Mary L. Disis |
| author_sort | William R. Gwin |
| collection | DOAJ |
| description | <b>Background/Objectives</b>: Regulatory T cells (Treg) suppress immunity in the tumor microenvironment, are linked to poor prognosis across breast cancer subtypes, and suppress the cytolytic function of cytotoxic CD8+ T cells. Denileukin diftitox, a diphtheria toxin (DT)/IL-2 fusion protein, targets and depletes Tregs. This Phase II study aimed to assess the safety of denileukin diftitox and its effect on Tregs and tumor growth in patients with advanced breast cancer. <b>Methods</b>: This single-arm Phase II study of denileukin diftitox enrolled patients with refractory stage IV breast cancer. Patients received denileukin diftitox 18 mcg/kg/day IV for Days 1–5 every 21 days for up to six cycles. Toxicity was assessed using CTCAE v3.0 and tumor response was evaluated per RECIST criteria. Blood samples were collected to analyze Tregs by flow cytometry and anti-DT antibodies by ELISA. <b>Results</b>: Fifteen patients with stage IV breast cancer were enrolled. Four patients completed all planned denileukin diftitox infusions and achieved stable disease (27%, 95% CI [0.08, 0.55]). Two patients (13%) discontinued due to toxicity, and nine patients (60%) discontinued due to progressive disease. Eleven patients experienced at least one grade 3 or 4 adverse event. Although there was a general reduction in peripheral blood Tregs, the difference in CD4+CD25+FOXP3+ Tregs levels post-treatment was not statistically significant (<i>p</i> = 0.10). Six patients (40%) achieved <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>≥</mo></mrow></semantics></math></inline-formula>25% reductions in Tregs. A significant increase in anti-DT IgG antibodies was observed post-treatment (<i>p</i> < 0.005). <b>Conclusions</b>: Denileukin diftitox demonstrated moderate toxicity in this advanced breast cancer cohort. Denileukin diftitox modulated regulatory T cells. However, the majority of patients experienced disease progression in the study. |
| format | Article |
| id | doaj-art-35d00e26ebb74b419a02cb575de57968 |
| institution | DOAJ |
| issn | 2076-393X |
| language | English |
| publishDate | 2025-01-01 |
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| spelling | doaj-art-35d00e26ebb74b419a02cb575de579682025-08-20T03:12:01ZengMDPI AGVaccines2076-393X2025-01-0113211710.3390/vaccines13020117A Phase II Study of Denileukin Diftitox in Patients with Advanced Treatment Refractory Breast CancerWilliam R. Gwin0Lupe G. Salazar1James Y. Dai2Doreen Higgins3Andrew L. Coveler4Jennifer S. Childs5Rosie Blancas6Yushe Dang7Jessica Reichow8Meredith Slota9Hailing Lu10Mary L. Disis11Cancer Vaccine Institute, University of Washington, 850 Republican Street, Box 358050, Seattle, WA 98195, USACancer Vaccine Institute, University of Washington, 850 Republican Street, Box 358050, Seattle, WA 98195, USAFred Hutchinson Cancer Center, 1100 Fairview Ave. N., Seattle, WA 98109, USACancer Vaccine Institute, University of Washington, 850 Republican Street, Box 358050, Seattle, WA 98195, USACancer Vaccine Institute, University of Washington, 850 Republican Street, Box 358050, Seattle, WA 98195, USACancer Vaccine Institute, University of Washington, 850 Republican Street, Box 358050, Seattle, WA 98195, USABreastlink Medical Group, 230 S Main St, #100, Orange County, CA 92868, USACancer Vaccine Institute, University of Washington, 850 Republican Street, Box 358050, Seattle, WA 98195, USACancer Vaccine Institute, University of Washington, 850 Republican Street, Box 358050, Seattle, WA 98195, USACancer Vaccine Institute, University of Washington, 850 Republican Street, Box 358050, Seattle, WA 98195, USASeattle Genetics (Pfizer), 21823 30th DR SE, Bothell, WA 98021, USACancer Vaccine Institute, University of Washington, 850 Republican Street, Box 358050, Seattle, WA 98195, USA<b>Background/Objectives</b>: Regulatory T cells (Treg) suppress immunity in the tumor microenvironment, are linked to poor prognosis across breast cancer subtypes, and suppress the cytolytic function of cytotoxic CD8+ T cells. Denileukin diftitox, a diphtheria toxin (DT)/IL-2 fusion protein, targets and depletes Tregs. This Phase II study aimed to assess the safety of denileukin diftitox and its effect on Tregs and tumor growth in patients with advanced breast cancer. <b>Methods</b>: This single-arm Phase II study of denileukin diftitox enrolled patients with refractory stage IV breast cancer. Patients received denileukin diftitox 18 mcg/kg/day IV for Days 1–5 every 21 days for up to six cycles. Toxicity was assessed using CTCAE v3.0 and tumor response was evaluated per RECIST criteria. Blood samples were collected to analyze Tregs by flow cytometry and anti-DT antibodies by ELISA. <b>Results</b>: Fifteen patients with stage IV breast cancer were enrolled. Four patients completed all planned denileukin diftitox infusions and achieved stable disease (27%, 95% CI [0.08, 0.55]). Two patients (13%) discontinued due to toxicity, and nine patients (60%) discontinued due to progressive disease. Eleven patients experienced at least one grade 3 or 4 adverse event. Although there was a general reduction in peripheral blood Tregs, the difference in CD4+CD25+FOXP3+ Tregs levels post-treatment was not statistically significant (<i>p</i> = 0.10). Six patients (40%) achieved <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>≥</mo></mrow></semantics></math></inline-formula>25% reductions in Tregs. A significant increase in anti-DT IgG antibodies was observed post-treatment (<i>p</i> < 0.005). <b>Conclusions</b>: Denileukin diftitox demonstrated moderate toxicity in this advanced breast cancer cohort. Denileukin diftitox modulated regulatory T cells. However, the majority of patients experienced disease progression in the study.https://www.mdpi.com/2076-393X/13/2/117denileukin diftitoxregulatory T-cellsbreast cancerimmunitytumor microenvironment |
| spellingShingle | William R. Gwin Lupe G. Salazar James Y. Dai Doreen Higgins Andrew L. Coveler Jennifer S. Childs Rosie Blancas Yushe Dang Jessica Reichow Meredith Slota Hailing Lu Mary L. Disis A Phase II Study of Denileukin Diftitox in Patients with Advanced Treatment Refractory Breast Cancer Vaccines denileukin diftitox regulatory T-cells breast cancer immunity tumor microenvironment |
| title | A Phase II Study of Denileukin Diftitox in Patients with Advanced Treatment Refractory Breast Cancer |
| title_full | A Phase II Study of Denileukin Diftitox in Patients with Advanced Treatment Refractory Breast Cancer |
| title_fullStr | A Phase II Study of Denileukin Diftitox in Patients with Advanced Treatment Refractory Breast Cancer |
| title_full_unstemmed | A Phase II Study of Denileukin Diftitox in Patients with Advanced Treatment Refractory Breast Cancer |
| title_short | A Phase II Study of Denileukin Diftitox in Patients with Advanced Treatment Refractory Breast Cancer |
| title_sort | phase ii study of denileukin diftitox in patients with advanced treatment refractory breast cancer |
| topic | denileukin diftitox regulatory T-cells breast cancer immunity tumor microenvironment |
| url | https://www.mdpi.com/2076-393X/13/2/117 |
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